Inhalers for the inhalation of pharmaceutical preparations packed in capsules wherein the capsules are moved during the inhalation, are already known. An inhaler of this type is known, for example, from German Offenlegungsschrift 1,566,604. The inhaler described therein comprises a device for receiving the capsules which has propeller-like wings and is mounted coaxially with the longitudinal axis of the apparatus. During inhalation, the device with the capsule is set rotating by the apparatus.
Whereas in the inhaler described above the pharmaceutical capsule is fixed in a movable part of the apparatus and is moved therewith, French patent application Ser. No. 2,146,202 describes an inhalation apparatus with a flat cylindrical chamber in which only the capsule itself moves. The capsule, which is opened at its ends, is driven by air flowing tangentially inwards and rotates about its transverse axis during inhalation.
Both of these known inhalers have the major disadvantage that the pharmaceutical composition is expelled unevenly. Some capsules are emptied virtually entirely while others still contain considerable amounts of pharmaceutical preparation after the inhalation process. This is the case particularly with very finely divided (micronized) pharmaceutical preparations.